1. Field of the Invention
The invention relates to the field of the propulsion of the spacecraft and the use of space environment. More particularly, the present invention relates to a variable specific impulse chemical-electromagnetic hybrid propeller based on a combination of chemical propulsion and electric propulsion methods.
2. Description of the Prior Art
Space propulsion is used during the period after the spacecraft has launched. Its function is to provide power to the mission of the spacecraft orbit transfer, state remaining, high-precision directing, orbit maneuver or the like.
The propulsion technique can be generally divided into chemical propulsion and electric propulsion, as well as some other propulsion techniques (such as solar sail, tethered propulsion, micro-magnetosphere propulsion or the like). At present, the main propeller of the most spacecraft adopts chemical propulsion. But the electric propulsion as an advanced propulsion technique is getting more and more attention.
Chemical propulsion is a propulsion technique using chemical energy to send the spacecraft into the reserved space course and realize the orbit maneuver. The most prominent feature of chemical propulsion is to provide high-thrust, has been the most used technique in the space field. The chemical engine is used in the present long-life tri-axial attitude control stabilized satellite and spin satellite as a controlling and executing assembly. The chemical propulsion technique is the most mature and used propulsion technique. However, with great development of the range and depth the human use and explore outer space, the chemical propulsion cannot satisfy the demand of future space missions. The biggest shortcoming of chemical propulsion is the low energy density and low specific impulse. The specific impulse of the single-unit chemical propeller is only about 200s, the specific impulse of the double-units chemical propeller is only about 325s, and which approach the limit of the chemical propulsion technique (Reference 1: Reed, Brian D. “On-Board Chemical Propulsion Technology,” NASA TM-2004-212698; Reference 2: Gulczinski F. In-Space Propulsion. AIAA-2003-2588; Reference 3: Sackheim R. Overview of United States Space Propulsion Technology and Associated Space Transportation Systems. Journal of Propulsion and Power. Vol. 22, No. 6, 2006; Reference 4: Wilson F. Recent Advances in Satellite Propulsion and Associated Mission Benefits. AIAA-2006-5306). Because of the low energy density and low specific impulse, the chemical propeller must carry a great amount of fuel, resulting in the huge weight and low reliability of the spacecraft system. The chemical propulsion cannot satisfy the demand of spacecraft mission, such as orbit maneuver, long-lifetime working and deep space exploration.
Electric propulsion provides energy to the propellant using the electricity generated and produced by the solar panel and nuclear reactor, to make the propellant producing the jet velocity far more than the common chemical propeller. The specific impulse of the electric propeller is high and can reach 1000s-80000s (based on the variable working theory), reduce the system quality, save the propellant, and improve the working-life of the spacecraft. Besides applying in the long-life communication satellite to improve the performance of the satellite platform, the electric propulsion can complete the tasks which the common propulsion system is unable to do. So the electric propeller is the important developing trend of the propulsion technique at home and abroad, which is gradually replacing a part of the chemical propeller. The shortcoming of the electric propulsion is the low propulsion force, the propulsion force of the common electric propeller about kw power is at about millinewton level, which is not suitable for executing the mission that needs high speed value such as orbit maneuver (Reference 9: A. G. Accettura, et. al. Advanced Propulsion Systems: Mission Scenarios, Critical Overview, and Key Technologies for New Demands, AIAA 2001-3517, 2001; 10 Advanced Propulsion Concepts, NASA JPL, 1989), which greatly restricts the future applying range of electric propulsion.
The important developing trend of the spacecraft at home and abroad is long-time in orbit, high-speed maneuver. Long-time in orbit needs the longer life-time of the spacecraft, and high-speed maneuver needs the spacecraft to be more agile and high ability of orbit transfer. To achieve the two goals, firstly it needs to improve the level of the space propulsion technique. The working-life of the propulsion system is a necessary factor to determine the working-life of the spacecraft. When the propeller is stopped, so does the satellite. Improving the specific impulse of the propeller can reduce the fuel consumption of the propeller, with the same fuel amount, high specific impulse propeller can work longer, and prolong the spacecraft life. The high speed maneuver spacecraft needs high speed value, such as large propulsion force, to achieve the orbit transfer quickly. At present, the chemical propulsion and electric propulsion can separately satisfy one of the factors and cannot simultaneously achieve large propulsion force and high specific impulse.
The invention provides the chemical-electromagnetic hybrid propulsion technique, combining the chemical propulsion and electric propulsion, and has the merit of the large propulsion force and high specific impulse, conquer the shortcoming of the two. It can be applied globally at variable spacecraft.